Swivel castors, particularly for shopping trolleys

ABSTRACT

A swivel castor for use on appliances such as shopping trolleys, which are conveyed on a ribbed or grooved conveyors comprises a castor fork with a running wheel and a tracking wheel arranged for rotation with and on the same axle as the running wheel. The tracking wheel is movable vertically in respect of the running wheel so that when the appliance is placed on the conveyor the tracking wheel can drop into a groove thereof. While the castor is running on a flat floor the tracking wheel hold a locking mechanism in inoperative position. When the tracking wheel drops into a groove the locking mechanism locks the wheel against running movement. The locking mechanism also includes a vertically movable member which follows the downward movement of the tracking wheel to lock the castor against swivelling movement. The latter member may be a pawl which engages ratchet teeth on the backset bearing or in an incision or groove in the castor fork. The vertical movement of the member can be controlled by the periphery of the tracking wheel or by an upper extension of the bearing disc of the tracking wheel.

United States Patent [191 Stosberg et al.

[451 Aug. 14, 11973 SWIVEL CASTORS, PARTICULARLY FUR SHOPPING TROLLEYS[75] Inventors: Herbert Stosberg; Horst Fleischmann, both ofWermelskirchen-Tente, Rhineland; Giinter Reinhards,Wermelskirchen/Rhineland; Siegfried Engels, Wermelskirchen-Tente,Rhineland, all of Germany [73] Assignee: Tente-Rollen Gesellschatt MitBeschrankter Haftung Companie, Wermelskirchen-Tente ap Rhineland,Germany [22] Filed: June 3, 1971 [211 App]. N0.: 149,600

[30] Foreign Application Priority Data Feb. 6, 1971 Germany P 21 05547.0

[52] US. Cl. 16/35, 188/5 [51] Int. Cl B60b 33/00 [58] Field of Search16/35, 35 D; 188/5, 188/32 [56] References Cited UNlTED STATES PATENTS3,305,064 2/1967 Mullis et a1. 188/5 3,608,693 9/1971 Stosberg et al.16/35 Primary Examiner-James T. McCall Assistant Examiner-Doris L.Troutm an Attorney-Burgess, Dinklage & Sprung [57] ABSTRACT A swivelcastor for use on appliances such as shopping trolleys, which areconveyed on a ribbed or grooved conveyors comprises a castor fork with arunning wheel and a tracking wheel arranged for rotation with and on thesame axle as the running wheel. The tracking wheel is movable verticallyin respect of the running wheel so that when the appliance is placed onthe conveyor the tracking wheel can drop into a groove thereof. Whilethe castor is running on a flat floor the tracking wheel hold a lockingmechanism in inoperative position. When the tracking wheel drops into agroove the locking mechanism locks the wheel against running movement.The locking mechanism also includes a vertically movable member whichfollows the downward movement of the tracking wheel to lock the castoragainst swivelling movement. The latter member may be a pawl whichengages ratchet teeth on the backset bearing or in an incision or groovein the castor fork. The vertical movement of the member can becontrolled by the periphery of the tracking wheel or by an upperextension of the bearing disc of the tracking wheel.

17 Claims, 20 Drawing Figures PATENIE AL"; 1 4 8973 sum 03 0F 10PAIENIEW 1 3,751,757

SHEET 07 HF 10 PAIENIEU we 1 41975 SHEET 08 0F 10 SWIVEL CASTORS,PARTICULARLY FOR SHOPPING TROLLlEY The invention relates to a swivelcastor, intended particularly for use with shopping trolleys inself-service stores, where passage from one floor to another is effectedby way of stairs or moving stairways, which are ribbed so thatself-service customers using the stairs or moving stairways can taketheir shopping trolleys with them. The invention can however also beused for industrial or other purposes where it is desired to conveymobile appliances on ribbed conveyor belts.

In order that shopping trolleys can be taken along without danger inself-service stores even on conveyor belts or moving stairways ribbed inthis manner, it is known to lock the swivel castors or other castors ofthe shopping trolley, in respect of the running mobility of theirrunning wheels, during the period in which it is taken along on theconveyor path, until the castors reach a guard plate at the end of theconveyor belt and arrive again on a level floor. For this purpose allthe castors, or individual castors, of the shopping trolley are eachprovided with a vertically movable sensing member in continuous contactwith the floor and when the sensing member dips into a groove in theconveyor belt a locking mechanism is actuated which locks the runningwheel in such a way as to prevent it running, as is described andillustrated in connection with a multiplicity of forms of embodiment inGerman Gebrauchsmuster No. 67 51 035 and in US. Pat. No. 3608693 (US.Pat. application Ser. No. 814 961) for which the application was filedon the th Apr. 1969.

In a particularly favourable form of embodiment such automaticallyself-locking castors take the form of a swivel castor with a verticallymovable sensing member in the form of a conjointly running sensor wheelwhich is arranged parallel to the running wheel and located together.with the running wheel on the axle of the running wheel and whichtherefore follows the movements of the running wheel on a paralleltrack, for which reason it will be termed in what follows a trackingwheel. The said tracking wheel conjointly rotating parallel to therunning wheel is however vertically movable in relation to the runningwheel axis and hence relatively to the running wheel. This means thatthe tracking wheel rotating conjointly parallel to the running wheel isin continuous contact with the floor and when passing in transition onto the ribbed conveyor stretch can dip into a groove in the conveyorbelt or moving track. As a result of this sinking movement the trackingwheel conjointly rotating as a sensing member releases a lockingmechanism which brakes the running wheel in respect of its runningmobility. This means that the swivel castors and hence the shoppingtrolley remain locked during entrainment on the conveyor stretch until,at the end of the ribbed conveyor belt, the lowered tracking wheels areraised again out of the grooves of the conveyor belt by its guard plate.

'With such swivel castors, which possess a vertically movable sensingmember in the form of a vertically movable tracking wheel conjointlyrotating parallel to the running wheel and on the running wheel axle, adisc-shaped tracking wheel dipped into a groove of a conveyor belt orother travelling platform provides a sufficiently strong lateral holdingpower for the swivellably movable per se swivel castor, if the ribbedtravelling platform consists of metal, for instance light metalsectional elements, so that then the swivel castors cannot swivel duringentrainment on the conveying stretch. For some time however travellingplatforms with rubber sectional elements have been used. However, thecomparatively soft rubber ribs of such travelling platforms do not givesufficient lateral hold to the conjointly rotating disc-shaped trackingwheel acting as vertically movable sensing member after the dipping intoa groove in the rubber belt, so that there is a danger of the swivelcastors inadvertently swivelling during the entrainment on the conveyingstretch and hence it is possible for the shopping trolley or the like toescape sideways, which might cause an accident.

An object of the invention is to avoid this disadvantage and to makesuch swivel castors as possess a vertically movable sensing member inthe form of a vertically movable tracking wheel conjointly rotatingparallel to the running wheel and on the running wheel axle, also safelyusable for such ribbed moving platforms and conveyor belts as consist ofrubber sectional elements or other soft material and which do not givesufficient lateral holding strength against swivelling to the trackingwheels after the dipping into the grooves in the conveyor belt.

The novel swivel castor for mobile appliances to be entrained orconveyed on ribbed or grooved conveyor belts, which castor isparticularly designed for shopping trolleys in self-service stores andwhich has a vertically movable sensing member in the form of avertically movable tracking wheel conjointly rotating parallel to therunning wheel and on the running wheel axle, which tracking wheel is incontinuous contact with the floor and which on dipping into a groove ofthe conveyor belt releases a locking mechanism locking the runningmobility of the running wheel, is characterised in accordance with thebasic idea of the invention in that the swivel castor also has avertically movable locking member controlled by the conjointly rotatingtracking wheel, for additionally locking the swivelling mobility of thecastor fork, which vertically movable locking member is continuouslyraised when the conjointly rotating tracking wheel is travelling over alevel floor and remains raised, and when the conjointly rotatingtracking wheel dips into a groove in the conveyor belt than the verticalmovement of the conjointly rotating tracking wheel can follow andthereby it can sink into its locking position and thus can effect thelockin of the castor fork. v

The control of the vertically movable locking member, which serves forthe additional locking of the swivelling mobility of the castor fork,can be effected from the conjointly rotating tracking wheel in anysuitable manner. In an advantageous form of embodiment of the inventionthe vertically movable locking member is controlled and raised by abearing disc of the conjointly rotating tracking wheel. For this purposethe bearing disc of the conjointly rotating tracking wheel can have anupper extension, which controls and raises the locking member. Evensimpler and more advantageous is a form of embodiment of the inventionin which the vertically movable locking member is simply applied on theperiphery of the conjointly rotating tracking wheel and is therebylifted and lowered by the wheel periphcry.

The vertically movable locking member which is controlled by theconjointly rotating tracking wheel and serves for the additional lockingof the swivelling mobility of the castor fork, may be of any suitabletype and construction. In an advantageous form of embodiment of theinvention the vertically movable locking member takes the form of alocking pawl which engages in the catch or locking position as theconjointly rotating tracking wheel sinks down, and is released againfrom its catch (locking) position as the conjointly rotating trackingwheel rises again.

Particular advantages are offered by a modification of the basic idea ofthe invention, which is characterised in that the pawl, which iscontrolled by the conjointly rotating tracking wheel and serves foradditionally locking the swivelling mobility of the castor fork, issupported in the hollow of the castor fork and as the conjointlyrotating tracking wheel sinks can engage in stationary ratchet teeth onthe swivel castor rear or back-set bearing, thereby also locking theswivelling mobility of the castor fork. In an advantageous form ofembodiment of this modification of the invention the pawl is supportedby one end on a spindle in the fork hollow. In another form ofembodiment of this modification of the invention the pawl takes the formof a two-armed lever which is supported on a spindle in the fork hollow.

In order that the vertically movable locking pawl can follow thevertical movement of the conjointly rotating tracking wheel as it dipsin, the said pawl can be springloaded, the spring pressing the pawldownwards and the pawl being raised against its pressure when travellingover a level floor by the conjointly rotating tracking wheel.

The vertically movable pawl controlled by the conjointly rotatingtracking wheel, for additionally locking the swivelling mobility of thecastor fork, which is preferably supported in the hollow of the saidcastor fork, simply lies, in an especially simple form of embodiment onthe periphery of the conjointly rotating tracking wheel and can thusfollow its sinking and rising movement. Advantageously the pawl isapplied by a projection of noise-reducing elastic material on theperiphery of the conjointly rotating tracking wheel. In another form ofembodiment the pawl lies on an upper extension of the bearing disc ofthe conjointly rotating tracking wheel and can thus follow its sinkingmovement. The pawl can however also be articulately connected with theupper extension of the bearing disc of the conjointly rotating trackingwheel in any suitable manner in such a way that the pawl is compelled tofollow the vertical movement of the conjointly rotating tracking wheel.

In another form of embodiment of the invention the vertically lowerablepawl which is controlled by the conjointly rotating tracking .wheel, isnot a constituent of the castor fork, but instead is supported on thefixed swivel castor rear or back-set bearing and can then lockinglyengage in an incision or groove or the like in the castor fork, in orderto lock this additionally in respect of its swivelling mobility, as aresult of the sinking movement of the conjointly rotating trackingwheel. For this purpose the bearing disc of the conjointly rotatingtracking wheel can be made with an upper extension of suitable form,which during travel over a level floor closes the ratchet type incisionof the swivel castor fork and when the tracking wheel sinks, frees thefork incision for the catch engagement of the pawl, which thus as theconjointly rotating tracking wheel dips in a groove of the conveyor beltadditionally locks the swivelling mobility of the swivel castor fork.

In a further form of embodiment of the invention there is supported inthe swivel castor back-set bearing a vertically displaceable catch pin,which is provided with a lower locking disc, secured against twisting orrotation, that is to say in such a manner that when travelling over alevel floor the catch pin is continuously held by the conjointlyrotating tracking wheel in its top dead centre position, and when theconjointly rotating tracking wheel sinks, the catch pin sinks with itand can thereby engage by means of its lower locking disc in ratchetteeth provided in the hollow of the castor fork, so that through thesinking of the conjointly rotating tracking wheel the swivel castor forkis also additionally locked. In order to ensure that the verticallydisplaceable catch pin acting as locking member follows the verticalmovement of the conjointly rotating tracking wheel and is controlled bythis, the bearing disc of the conjointly rotating tracking wheel can beformed with an upper extension and a bracket applied against this, onwhich the vertically displaceable catch pin is applied by its lower endand maintains continuous contact by its own weight.

In the drawings are diagrammatically represented some examples ofembodiment of the invention.

FIG. 1 is a partly cut away view of a swivel castor with a locking pawlapplied on the tracking wheel and supported at one end, freely movableon a level floor.

FIG. 2 is a view, likewise partly cut away, of the freely-movable swivelcastor of FIG. I viewed in the direction of travel.

FIG. 3 corresponds to FIG. 1 and shows the swivel castor fully locked ona grooved conveyor belt, with the tracking wheel dipped into a conveyorbelt groove.

FIG. 4 corresponds to FIG. 2 and shows the fully locked swivel castor ofFIG. 3 viewed in the direction of travel.

FIG. 5 is another partly cut away view of a swivel castor with a lockingpawl supported at one end and controlled by the ball bearing disc of thetracking wheel, freely movable on a level floor.

FIG. 6 is also a partly cut away view of the freely movable swivelcastor of FIG. 5 viewed in the direction of travel.

FIG. 7 corresponds to FIG. 5 and shows the swivel castor completelylocked on a grooved conveyor belt,

with the tracking wheel dipped into a conveyor belt groove.

FIG. 8 corresponds to FIG. 6 and shows the completely locked swivelcastor of FIG. 7 viewed in the direction of travel.

FIG. 9 is another partly cut away view of a swivel castor with a lockingpawl formed as a two-armed lever and controlled by the ball bearing discof the tracking wheel, freely movable on a level floor.

FIG. 10 is also a partly cut away view of the freely movable swivelcastor of FIG. 9 viewed in the direction of travel.

FIG. 11 corresponds to FIG. 9 and shows the swivel castor completelylocked on a grooved conveyor belt, with the tracking wheel dipped in toa conveyor belt groove.

FIG. 12 corresponds to FIG. 10 and shows the completely locked swivelcastor of FIG. 11 viewed in the direction of travel.

FIG. 13 is a partly cutaway view of a swivel castor with a locking pawlsupported in the fixed swivel castor back-set or rear bearing, freelymovable on a level floor.

FIG. 14 is a partly cut away view of the freely movable swivel castor ofFIG. 13 viewed in the direction of travel.

FIG. 15 corresponds to FIG. 13 and shows the swivel castor completelylocked on a grooved conveyor belt with the tracking wheel dipped into aconveyor belt groove.

FIG. 16 corresponds to FIG. 14 and shows the completely locked swivelcastor of FIG. 15 viewed in the direction of travel.

FIG. 17 is another partly cut away view of a swivel castor with a catchpin provided with a locking disc and displaceable in the swivel castorback-set or rear bearing, freely movable on a level floor.

FIG. 18 is a partly cut away view of the freely movable swivel castor ofFIG. 17 viewed in the direction of travel.

FIG. 19 corresponds to FIG. 17 and shows the swivel castor completelylocked on'a grooved conveyor belt, with the tracking wheel dipped into aconveyor belt groove.

FIG. 20 corresponds to FIG. 18 and shows the com pletely locked swivelcastor of FIG. 19 viewed in the direction of travel.

The swivel castors illustrated are designed for shopping trolleys inself-service stores, which trolleys can be entrained on ribbed orgrooved conveyor belts. They have therefore a vertically movable sensingmember in the form of a tracking wheel 3 conjointly rotating parallel tothe running wheel 1 and on the running axle 2. The tracking wheel 3 ishowever movable in the vertical direction in relation to the runningwheel axle 2.

As can be seen from the cut away drawings in FIG. 4 and FIG. 12, thetracking wheel 3 in these examples of embodiment is rotatably supportedfor this purpose bilaterally between two ball bearing discs 4 and 5,which have a substantially larger bore 6 than the wheel hub 7 and aretherefore movable vertically in respect of the running wheel axle 2 andhence relatively to the running wheel 1. The two ball bearing discs 4and 5 are force-lockingly connected to one another by an annularintermediate component 8. The outer ball bearing disc 5 is verticallymovably guided by a cam 9 in a slot 10 of the castor fork 11, which cam9 prevents the wheel body of the tracking wheel 8, which wheel bodyconsists of the ball bearing discs 4 and 5 and the intermediatecomponent 8, from rotating on the hub 7 round the running wheel axle 2.A pressure spring 12 accommodated in the hollow wheel body presses thewheel body downwards and ensures that the tracking wheel 3 iscontinuously in contact with the floor and is urged to sink deeperbeyond the periphery of the run ning wheel 1. The tracking wheel 3 ismade so narrow at its periphery 13 that when travelling over a groovedconveyor belt 14 it can sink into one of the grooves 15, being urged todo so by the pressure spring 12. When such a dipping into a groove 15 ofthe conveyor belt 14 takes place, the tracking wheel 3 releases alocking mechanism locking the running mobility of the running wheel 1.This locking mechanism consists, in the examples of embodimentrepresented, of a pin 16 provided at the inner ball bearing disc 4, andof pocket-shaped ratchet notches 17 which are provided round the periphery of the wheel body 18 of the running wheel 1. As the disc-shapedwheel body of the tracking wheel 3, which wheel body consists of theball bearing discs 4 and 5 and the intermediate component 8, isprevented from rotating by the cam 9, the pin 16 locks the running wheel1 when a vertical dipping of the running wheel body 13 into a ratchetnotch 17 occurs, and thus locks the running wheel 1 in respect of itsrunning mobility. If in accordance with FIG. 2 and FIG. 10 the trackingwheel 3 is again raised, then the pin 16 leaves the ratchet notch 17 ofthe running wheel body 18 and thus frees the running wheel 1 again, sothat it can now again travel freely over a level floor.

The swivel castors illustrated have additionally furthermore avertically lowerable locking member 20, which is likewise controlled bythe conjointly rotating tracking wheel 33 and serves for locking thecastor fork 1 1 in respect of its swivelling mobility. When travellingover a level floor the vertically lowerable locking member 20 is andremains continuously raised by the conjointly rotating tracking wheel 3.When the conjointly rotating tracking wheel 3 dips into a groove 15 ofthe conveyor belt 14, the vertically movable locking member follows thevertical movement of the conjointly rotating tracking wheel v3 and sinkswith the tracking wheel 3 into its locking position, causing the lockingof the castor fork 11. In the case of the swivel castors of FIGS. 5 to 8and FIGS. 13 to 20, the vertically movable locking member 20 iscontrolled from one of the bearing discs 4 and 5 of the conjointlyrotating tracking wheel 3 and is raised, for which purpose in theseexamples the bearing disc 5 of the conjointly rotating tracking wheel 3has an upper extension 19 which controls and raises the locking member20. In the case of the swivel castors of FIGS. 1 to 4 and FIGS. 9 to 12the vertically movable locking member 20 lies on the wheel periphery 13of the conjointly rotating tracking wheel 3 and is controlled and raisedby the wheel periphery l3.

In the case of the swivel castors of FIGS. 1 to 12 the locking member 20in each case is formed by a vertically movable locking pawl 21, whichwhen the conjointly rotating tracking wheel 3 sinks down, engages in itscatch or locking position. The locking pawl 21 is in each case supportedin the hollow 28 of the castor fork 1 1 and when a sinking of theconjointly rotating tracking wheel 3 takes place can engage that is,catch, in fixed teeth 29 on the swivel castor back-set or rear bearing30. In the case of the swivel castors shown in FIGS. 1 to 8 it is aquestion in each case of a locking pawl 22, which is supported at oneend on a spindle or axle 31 in the fork hollow 28. In the case of theswivel castor of FIGS. 7 to 10 the locking pawl takes the form of atwo-armed lever 23, which is likewise supported on an axle or spindle 31in the fork hollow 28. In all three cases the pawls 21,22 or 23 arelocated by a spring 32, which is partly a leaf spring and partly aspring clip. The spring 32 presses the pawls 21,22 or 23 in each casedownwards. When travelling over a level floor the pawls 21,22 or 23 arelifted by the conjointly rotating tracking wheel 3 against the pressureof the spring 32. In the case of the swivel castors of FIGS. 1 to 4 andFIGS. 9 to 12 the pawls 22 and 23 are applied by a projection 33,consisting of noise-reducing elastic material, on the wheel periphery 13of the conjointly rotating tracking wheel 3 and can thus follow thesinking movement of the tracking wheel 3. In the case of the swivelcastors of FIGS. to 8 the pawl 22 is applied on the upper extension 19of the bearing disc 5 of the conjointly rotating tracking wheel 3, as aresult of which the said pawl 22 can follow the sinking movement of thetracking wheel 3. instead of this arrangement however it is alsopossible for the pawl 22 to be articulately connected to the upperextension 19 of the bearing disc 5 of the conjointly rotating trackingwheel 3, then being compelled to follow the vertical movements of thetracking wheel 3.

in the case of the swivel castor shown in FIGS. 13 to 16 the swivelcastor back-set bearing 30 has a fixed cap 34, in which a small lockingpawl 24 is supported in such a way as to be vertically movable. The pawl24 can engage in an incision 35 of the castor fork 11, thus locking thecastor fork 11 in such a way as to prevent it from swivelling. The pawl24 is controlled by the bearing disc 5 of the conjointly rotatingtracking wheel 3 by means of an upper extension 19. When travelling overa level floor the tracking wheel 3 lifts the pawl 24 until the upperextension 19 of the bearing disc 5 completely closes the lockingincision 35 of the swivel castor fork 11. By this the locking pawl 24 isagain released so that then the castor fork is again free to moveswivellingly. if when travelling over a ribbed conveyor belt 14 thetracking wheel 3 clips into one of its grooves 15 (FIGS. 15 and 16).then the bearing disc 5 simultaneously sinks downwards and its upperextension 19 frees the fork incision 35 so as to permit catch engagementof the locking pawl 24, so that then the castor fork 11 is braked.

in the case of the swivel castor of FIGS. 17 to 20 a catch pin 26 issupported in the swivel castor back-set bearing 30, which pin isvertically movable and is accured against rotation. A locking disc isprovided at the lower end of the catch pin 26 in the fork hollow 28. Thevertically displaceablc catch pin 26 is applied under the influence ofits own weight by its lower end 27 on a bracket 36, which is provided onan upper extension 19 of the bearing disc 5 of the conjointly rotatingtracking wheel 3. Because of this arrangement the verticallydisplaceable catch pin 26 can then follow the vertical movements ofthetracking wheel 3. When travelling over a level floor the catch pin 26 isheld by its lower locking disc 25 continuously in its top dead centreposition. if the swivel castor arrives on a ribbed conveyor belt 14,then the tracking wheel 3 can dip into one of the grooves 15 of theconveyor belt 14. When this sinking of the conjointly rotating trackingwheel 3 takes place, its bearing disc 5 also sinks, which causes thecatch pin 26 applied on the bracket 36 to sink conjointly also, underits own weight. This causes the lower locking disc 25 of the catch pin26 to engage in ratchet teeth 37 which are fixed in the hollow 28 of thecastor fork 11 to this. When the tracking wheel 3 rises, the bracket 36also presses the catch pin 26 up again, because of which its lockingdisc 25 leaves the ratchet teeth 37 of the fork 11, so that then thecastor fork 11 is freely movable again and the swivel castor can roll inany direction desired over the level floor.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A swivel castor for mobile appliances which are entrained or conveyedon grooved conveyor belts, particularly for shopping trolleys inself-service stores, said castor comprising a swivellable castor fork,an axle held by said fork a running wheel mounted on said axle, avertically movable tracking wheel mounted freely tumably on said axleparallel to the running wheel to follow said running wheel in continuouscontact with the floor, a locking mechanism and means operableonmovement of said tracking wheel into a groove of said conveyor belt tocause said locking mechanism to lock the running wheel against runningmobility, characterised in that the castor further comprises avertically movable member controlled by said tracking wheel for alsolocking said castor fork against swivelling mobility, said lockingmember being arranged to remain continuously raised during travel of thecastor on a level floor, and to follow the movement of the trackingwheel when entering a groove in the conveyor belt to sink into itslocking position and thus effect locking of the castor fork.

2. A swivel castor as claimed in claim 1, wherein the vertically movablelocking member is controlled and riased by a bearing disc of thetracking wheel.

3. A swivel castor as claimed in claim 2, wherein the bearing disc ofthe tracking wheel has an upper extension which controls and raises thelocking member.

4. A swivel castor as claimed in claim 1, wherein the vertically movablelocking member is applied on the wheel periphery of the tracking wheeland is controlled and raised by the said wheel periphery.

5. A swivel castor as claimed in claim 1, wherein the locking member isa pawl which engages in its locking position when the tracking wheelsinks relatively to the running wheel.

6. A swivel castor as claimed in claim 5, wherein the pawl is supportedin the hollow of the castor fork, and when the tracking wheel sinksdown, said pawl engages fixed teeth on the holding device of the castorback-set or rear bearing.

7. A swivel castor as claimed in claim 6, wherein the pawl is supportedby one of its ends on an axis or spindle in the fork hollow.

8. A swivel caster as claimed in claim 6, wherein the pawl is atwo-armed level which is supported on an axle or spindle in the forkhollow.

9. A swivel castor as claimed in claim 8 wherein the pawl isspring-loaded by a spring which presses the pawl downwards, and the saidpawl is raised against the spring pressure by the tracking wheel.

10. A swivel castor as claimed in claim 3 wherein the pawl is applied onthe wheel periphery of the tracking wheel and can thus follow itssinking movement.

11. A swivel castor as claimed in claim 10, wherein the pawl is appliedby a projection of noise-reducing pawl is supported on the fixed holdingdevice of the castor back-set or rear bearing and can catch-engage in anincision or groove or the like in the castor fork.

15. A swivel castor as claimed in claim 14 wherein an upper extension ofthe bearing disc of the tracking wheel during travel over a level floorcloses the locking with it and can thereby catch-engage by means of itslower locking disc in ratchet teeth in the hollow of the castor fork.

17. A swivel castor as claimed in claim 16, wherein the verticallydisplaceable catch pin is applied by' its lower end on a bracket of anupper extension of a bearing disc of the tracking wheel and can thusfollow its vertical movements.

i 4 W 4 t

1. A swivel castor for mobile appliances which are entrained or conveyedon grooved conveyor belts, particularly for shopping trolleys inself-service stores, said castor comprising a swivellable castor fork,an axle held by said fork a running wheel mounted on said axle, avertically movable tracking wheel mounted freely turnably on said axleparallel to the running wheel to follow said running wheel in continuouscontact with the floor, a locking mechanism and means operable onmovement of said tracking wheel into a groove of said conveyor belt tocause said locking mechanism to lock the running wheel against runningmobility, characterised in that the castor further comprises avertically movable member controlled by said tracking wheel for alsolocking said castor fork against swivelling mobility, said lockingmember being arranged to remain continuously raised during travel of thecastor on a level floor, and to follow the movement of the trackingwheel when entering a groove in the conveyor belt to sink into itslocking position and thus effect locking of the castor fork.
 2. A swivelcastor as claimed in claim 1, wherein the vertically movable lockingmember is controlled and riased by a bearing disc of the tracking wheel.3. A swivel castor as claimed in claim 2, wherein the bearing disc ofthe tracking wheel has an upper extension which controls and raises thelocking member.
 4. A swivel castor as claimed in claim 1, wherein thevertically movable locking member is applied on the wheel periphery ofthe tracking wheel and is controlled and raised by the said wheelperiphery.
 5. A swivel castor as claimed in claim 1, wherein the lockingmember is a pawl which engages in its locking position when the trackingwheel sinks relatively to the running wheel.
 6. A swivel castor asclaimed in claim 5, wherein the pawl is supported in the hollow of thecastor fork, and when the tracking wheel sinks down, said pawl engagesfixed teeth on the holding device of the castor back-set or rearbearing.
 7. A swivel castor as claimed in claim 6, wherein the pawl issupported by one of its ends on an axle or spindle in the fork hollow.8. A swivel castor as claimed in cLaim 6, wherein the pawl is atwo-armed level which is supported on an axle or spindle in the forkhollow.
 9. A swivel castor as claimed in claim 5 wherein the pawl isspring-loaded by a spring which presses the pawl downwards, and the saidpawl is raised against the spring pressure by the tracking wheel.
 10. Aswivel castor as claimed in claim 5 wherein the pawl is applied on thewheel periphery of the tracking wheel and can thus follow its sinkingmovement.
 11. A swivel castor as claimed in claim 10, wherein the pawlis applied by a projection of noise-reducing elastic material on thewheel periphery of the tracking wheel.
 12. A swivel castor as claimed inclaim 5, wherein the pawl is applied on an upper extension of thebearing disc of the tracking wheel and can thus follow its sinkingmovement.
 13. A swivel castor as claimed in claim 12, wherein the pawlis articulately connected with the upper extension of the bearing discof the tracking wheel.
 14. A swivel castor as claimed in claim 5,wherein the pawl is supported on the fixed holding device of the castorback-set or rear bearing and can catch-engage in an incision or grooveor the like in the castor fork.
 15. A swivel castor as claimed in claim14 wherein an upper extension of the bearing disc of the tracking wheelduring travel over a level floor closes the locking incision or notch ofthe swivel castor fork and when the tracking wheel sinks down, frees thefork incision or notch for the catch engagement of the pawl.
 16. Aswivel castor as claimed in claim 1, wherein there is supported in theswivel castor back-set or rear bearing a vertically displaceable catchpin secured against twisting or rotation with a lower locking disc whichduring travel over a level floor is held by the tracking wheelcontinuously in its top dead centre and which when the tracking wheelsinks down sinks down with it and can thereby catch-engage by means ofits lower locking disc in ratchet teeth in the hollow of the castorfork.
 17. A swivel castor as claimed in claim 16, wherein the verticallydisplaceable catch pin is applied by its lower end on a bracket of anupper extension of a bearing disc of the tracking wheel and can thusfollow its vertical movements.